Ultra high molecular weight polyethylene is well known in the art. Articles made from ultra high molecular weight polyethylene possess properties such as toughness, impact strength, abrasion resistance, low coefficient of friction, gamma resistance, and resistance to attack by solvents and corrosive chemicals. Because of the favorable attributes associated with ultra high molecular weight polyethylene, ultra high molecular weight polyethylene has been utilized in a variety of applications, such as load-bearing components of articulating joint prostheses, vibration dampener pads, hydraulic cylinders, sports equipment, including, but not limited to, skis, ski poles, goggle frames, protective helmets, climbing equipment, and in specialized applications in aerospace.
UHMWPE polymers can be processed by compression molding, ram extrusion, gel spinning, and sintering. However, these conventional processes have one or more undesirable feature or attribute, such as requiring high solvent levels, processing above the melt temperature of the UHMWPE polymer, result in a non-porous structure, and/or are costly or slow to process due to the high viscosity of the UHMWPE polymer. Thus, there exists a need in the art for a process for making an UHMWPE article that is processed below the melt, has high strength, has a microstructure of nodes and fibrils for ease of processing, and is highly porous.